Axial fan wheel

ABSTRACT

An axial fan wheel, in particular for the radiator of a motor vehicle engine, is described. The axial fan wheel includes a crown ring having a multiplicity of rotor blades, a hub having an inner ring which is connected or connectable to a drive shaft, and having, for the purpose of torque transmission, connection surfaces along an outer periphery of the hub which are connected to the inner ring and to the crown ring. The hub has through-passages between the inner ring and the outer periphery. At least one element, arranged rotationally fixedly on the axial fan wheel inside the crown ring, is designed to maintain a pressure difference in the axial direction when the axial fan wheel rotates.

BACKGROUND Technical Field

The present disclosure relates to an axial fan wheel. In particular, anaxial fan wheel for the radiator of a motor vehicle engine and a utilityvehicle equipped therewith are described.

Description of Related Art

In order to supply ambient air to the radiator of a cooling circuit, anaxial fan wheel for generating a negative pressure at the radiator isarranged for example downstream of the radiator in the flow direction.Depending on ambient-air temperature and cooling power, a fan hub of 10the axial fan wheel has to transmit considerable mechanical power to therotor blades of the axial fan wheel, which power can be more than 10 kWin the utility vehicle sector. This gives rise to correspondingly largecentrifugal forces in the fan hub and, for the transmission of power andduring changes in rotational speed, large shear forces.

Document EP 1 519 052 B1 describes an axial fan wheel whose hub endsurface comprises a mechanism with displaceable aperture discs. When theaxial fan wheel rotates, the aperture discs close off the hub endsurface. When the fan is switched off, the hub end surface is partiallyopened by way of preload.

However, a mechanism, integrated into the rotating fan hub, with movingparts, in particular with aperture discs which are displaceable in thedirection of rotation with respect to the fan hub, hinders efficientoperation, in terms of power, of the axial fan wheel. The additionalrotating mass of the mechanism leads to an increase in the powerconsumption of the axial fan wheel and thus for example in the fuelconsumption. Also, a mechanism integrated into the fan hub is subjectedto the forces mentioned and, in the air stream, can jam due to dirt. Itis true that, for the purpose of reducing the rotating mass, it is inprinciple possible to provide the fan hub with permanent openings.However, as a result of the openings, the negative pressure built up onthe radiator side is reduced.

SUMMARY

It is therefore an object of the present disclosure to specify a moreenergy-efficient axial fan wheel which meets the load requirements forexample in the utility vehicle sector.

Said object is achieved by an axial fan wheel and a motor vehicleequipped therewith according to the independent patent claims.Advantageous embodiments and applications form the subject matter of thedependent patent claims and are explained in more detail hereinbelowwith partial reference to the figures.

According to one aspect, an axial fan wheel, in particular for theradiator of a motor vehicle engine, is provided. The axial fan wheelcomprises a crown ring having a multiplicity of rotor blades; and a hubhaving an inner ring which is connected or connectable to a drive shaft,and having, for the purpose of torque transmission, connection surfacesalong an outer periphery of the hub which are connected to the innerring and to the crown ring. The hub has through-passages between theinner ring and the outer periphery. At least one element, arranged in arotationally fixed manner on the axial fan wheel inside the crown ring,is designed to maintain a pressure difference in the axial directionwhen the axial fan wheel rotates.

The rotor blades can extend radially from the crown ring outside thecrown ring. The rotor blades can drive an air stream. The at least oneelement makes it possible to prevent recirculation (or backflow) of theair stream in the periphery of the hub (for example inside the outerperiphery).

Since the at least one element is arranged on the axial fan wheel in arotationally fixed manner, in particular without relative movement tothe hub, exemplary embodiments of the axial fan wheel are able to meetthe load and power requirements in the utility vehicle sector.Alternatively or additionally, on account of the through-passages, it ispossible, for the purpose of reducing the required driving power, inparticular in the case of changing rotational speeds, for the rotatingmass of the hub to be reduced.

The at least one element can prevent pressure equalization or pressurereduction of the air via the through-passages. The at least one elementmay in this case be designed without or without significantlycontributing to the rotating mass of the hub, for example since the atleast one element is not involved in the transmission of torque (fromthe inner ring to the crown ring via the connection surfaces).

The connection surfaces along the outer periphery may be realized by anouter ring and/or ring segments along the outer periphery. The outerring may be circumferentially closed. The ring segments may be spacedapart from one another. The connection surfaces may be situated in aplane of rotation of the axial fan wheel or of the hub.

The outer periphery, for example the outer ring and/or the ringsegments, may be arranged radially inside the crown ring. The inner ringmay be arranged radially inside the outer periphery. The transmission oftorque between the inner ring and the crown ring is able to take placeexclusively via the connection surfaces.

The hub may be of lightweight construction, in particular between theinner ring and the outer periphery (for example the outer ring).Alternatively or additionally, it is possible for the inner ring to besituated outside a plane of rotation of the connection surfaces (forexample outside a plane of rotation of the outer ring). For example, thehub may bulge or be curved in the direction of the drive shaft, at leastat the inner ring as a connection point.

Conventional fan hubs for the fan drive are designed in such a way thatthe fan hub itself separates the negative-pressure side (or fan suctionside) from the positive-pressure side (for example the enginecompartment), whereby, due to a wall thickness of the fan hub that isformed for the purpose of the torque transmission, the moment of inertiaof said hub is greater than in exemplary embodiments. If the moment ofinertia of the fan hub were to be reduced by way of openings, thecooling power, at the same rotational speed, would become poorer, and,to build up the same pressure difference, the rotational speed wouldhave to be increased. By contrast, exemplary embodiments having theelement fastened in a rotationally fixed manner on the axial fan wheelare able to prevent air recirculation without significantly increasingthe moment of inertia of the axial fan wheel or of the hub thereof. Thesame pressure difference can thus be generated at the same rotationalspeed with lower power consumption.

The at least one element may comprise an additional cover plate and/oran air guide device which counteracts the recirculation. The air guidedevice may comprise further rotor blades inside the periphery of thecrown ring. The air guide element may be joined with the hub integrallyin one piece (for example by forming the hub without additional mass) orscrewed on as an additional sheet. The lightweight construction of thehub with the through-passages allows for example fuel reduction withoutrecirculation of cooling air.

The pressure difference in the axial direction can be built up by therotating rotor blades, for example radially outside the crown ring. Thepressure difference in the axial direction can be maintained by the atleast one element radially inside the crown ring.

The inner ring may be connected or connectable to the drive shaft via apress fit. The axial fan wheel may be driven hydrostatically,electrically or mechanically (for example via a belt).

A surface portion, projected into the plane of rotation (that is to sayaxially), of the hub between the inner ring and the outer periphery (forexample outer ring) may be smaller than a surface portion, projectedinto the plane of rotation (that is to say axially), of thethrough-passages between the inner ring and the outer periphery (forexample outer ring). Alternatively or additionally, a radial width ofthe through-passages may be greater than a diameter of the inner ring(for example an inner diameter or inscribed-circle diameter) of theinner ring.

The at least one element may cover and/or (at least partially) close offthe interior of the crown ring and/or the through-passages between theinner ring and the outer periphery (for example outer ring). Thecovering or closing element is also referred to as a cover.

The at least one element may comprise further rotor blades. Furtherrotor blades may be integrally formed on the at least one element (forexample the cover).

The at least one element may comprise spokes for the transmission oftorque between the inner ring and the outer periphery (for example outerring). The spokes may be designed as further rotor blades. The hub mayhave the through-passages between the spokes.

The further rotor blades, which, for example, are formed by spokesand/or are integrally formed on the cover, may be inclined with respectto a plane of rotation of the axial fan wheel and/or may be curved inthe circumferential direction (or direction of rotation). The furtherrotor blades may include an angle of inclination with the plane ofrotation or may have a slope. The angle of inclination may be (forexample on the outer periphery or on the periphery of the outer ring) atleast 5° to 15°.

The at least one element may be arranged rigidly on the hub. The atleast one element may be immovable with respect to the hub (inparticular fixed in terms of rotation and pivoting with respect to thehub) during operation of the axial fan wheel. For example, a position ofthe at least one element with respect to the hub may be independent ofrotational speed.

The at least one element may be manufactured from a light metal (forexample aluminium) or from a fibre-composite material (for example withglass or carbon fibres). The at least one element, for example thecover, may be thin-walled. For example, an axial wall thickness of thecover may be less than an axial wall thickness of the hub. The at leastone element, for example the cover, may be manufactured from aluminiumsheet.

The at least one element, for example the cover, may be withoutcontribution to the transmission of torque (in particular withoutcontributing to the transmission of driving torque from the drive shaft)to the crown ring.

A diameter of the at least one element may be greater than an outerdiameter of the outer periphery (for example of the outer ring). Thediameter of the at least one element may be (at least substantially)equal to or less than an inner diameter of the crown ring.

The at least one element may be arranged offset with respect to the hubin the axial direction. Alternatively or additionally, the inner ringmay be arranged outside a plane of rotation defined by the connectionsurfaces or the outer ring. For example, the cover may be arranged on anupstream side of the plane of rotation defined by the connectionsurfaces or the outer ring. The inner ring may be arranged on adownstream side of the plane of rotation defined by the connectionsurfaces or the outer ring.

According to a further aspect, a motor vehicle, in particular a utilityvehicle, is provided. The motor vehicle comprises a fan arrangementhaving an axial fan wheel according to an embodiment of theabove-mentioned aspect. The fan arrangement may comprise a radiator forcooling an assembly of the drive train, for example an internalcombustion engine and/or an electrical traction energy storage device.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the disclosure are describedhereinbelow with reference to the appended drawings, in which:

FIG. 1 shows a diagrammatic view of a first exemplary embodiment of ahub for an axial fan wheel;

FIG. 2 shows a diagrammatic view of a second exemplary embodiment of ahub for an axial fan wheel;

FIG. 3 shows a perspective illustration of a fan arrangement with afirst exemplary embodiment of an axial fan wheel;

FIG. 4 shows a perspective illustration of a fan arrangement with asecond exemplary embodiment of an axial fan wheel;

FIGS. 5A and 5B show perspective illustrations of a fan arrangement witha third exemplary embodiment of an axial fan wheel; and

FIG. 6 shows a schematic sectional illustration of an exemplaryembodiment of the fan arrangement with axial fan wheel and radiatortrough.

DETAILED DESCRIPTION

FIG. 1 shows a first exemplary embodiment of an axial fan wheel which isgenerally identified by the reference sign 102. The axial fan wheelcomprises a multiplicity of rotor blades 104 which are bounded radiallyon the outside by a casing ring 106 and radially on the inside by acrown ring 108. On the crown ring 108, it is possible for crown webs 110to project radially to the inside, with fastening points for therotationally fixed connection (for example screwed connection) to a hub112.

The hub 112 comprises an inner ring 114 which is connectable to a driveshaft, and connection surfaces on an outer periphery 118 of the hub 112,for example an outer ring or segments of such a ring. The hub 112 isconnected to the crown ring 108 via the connection surfaces, for examplevia the outer ring.

For clarity of the description, it is assumed in the followingdescription that the connection surfaces are formed along the outerperiphery by an outer ring 118. Wherever the following text is gearedtowards the outer ring 118, this may be modified such that only segmentsof the described outer ring 118 are present and form the connectionsurfaces.

Torque (for example a driving torque and/or a deceleration torque of theaxial fan wheel 102) is transmissible via a region 116 between the innerring 114 and the outer ring 118. The intermediate region 116 comprises amultiplicity of through-passages 120.

The intermediate region 116 is of lightweight construction because ofthe through-passages 120. For example, the mass and/or the moment ofinertia of the intermediate region 116 is minimized under the constraintof the transmission of the torque between the inner ring 114 and theouter ring 118 of the hub 112.

In the exemplary embodiment shown in FIG. 1, the intermediate region 116comprises at least one ring which, for the purpose of transmitting thetorque, is connected, via radial webs, on the inside to the inner ring114 and on the outside to the outer ring 118. The inner radial webs andthe outer radial webs are circumferentially distributed in a uniformmanner, that is to say with equal angular spacings. For example, threeinner radial webs include in each case in pairs an angle of 120°.Likewise, three outer radial webs include in each case in pairs an angleof 120°. In this case, outer and inner webs are not arranged in radialalignment. For example, in the case of three inner radial webs and threeouter radial webs, each inner radial web includes an angle of 60° withan outer radial web. With double the number of webs, the correspondingangle is half as large.

FIG. 2 shows a second exemplary embodiment of a hub 112 for an axial fanwheel 102. Identical or functionally corresponding features aredesignated by corresponding reference signs in the figures.

The second exemplary embodiment of the hub 112 shown in FIG. 2comprises, in the intermediate region 116, a multiplicity of spokes 117which each extend radially from the inner ring 114 to the outer ring118. The through-passages 120 of the hub 112 are between the spokes 117.

In each exemplary embodiment of the hub 112, its lightweightconstruction can be achieved by a surface portion of the hub 112 in theintermediate region 116, which portion is smaller than a surface portionof the through-passages 120. For example, in the intermediate region 116between the inner ring 114 and the outer ring 118, the portion,projected onto the plane of rotation in the axial direction, of the hub112 (that is to say the closed surface portion of the intermediateregion 116) is smaller than the correspondingly projected portion of thethrough-passages 120.

Alternatively or additionally, a radial width of the intermediate region116 (for example the length of the spokes 117) is greater than adiameter 115 of the inner ring 114.

The axial fan wheel 102 further comprises (for example in combinationwith each above-mentioned exemplary embodiment of the hub 112) anelement which is arranged in a rotationally fixed manner on the axialfan wheel 102 inside the crown ring 108 and which is designed tomaintain a pressure difference in the axial direction when the axial fanwheel 102 rotates. The at least one element maintains the pressuredifference, for example in that the through-passages 120 are closed offor covered. Alternatively or additionally, on account of the rotation ofthe hub 112, the at least one element locally generates a pressuredifference, which corresponds to the pressure difference that is to bemaintained.

Advantageously, the at least one element does not or does notsignificantly contribute to the mass or the moment of inertia of the hub112 or of the axial fan wheel 102. For example, the at least one elementcomprises a thin-walled cover which prevents air recirculation (orpartial backflow) through the through-passages 120. Alternatively oradditionally, the at least one element comprises further rotor bladeswhich are integrally formed on a cover of the through-passages 120 orwhich are simultaneously part of the torque-transmitting structure inthe intermediate region 116.

FIG. 3 shows a first exemplary embodiment of the axial fan wheel 102 inthe context of an exemplary fan arrangement 100. The hub 112 of theaxial fan wheel 102 may comprise alternative or additional featuresaccording to each of the examples of the hub 112 that are described withreference to FIGS. 1 and 2.

Optionally, the outer ring 118 of the hub 112 comprises hub webs 122,projecting radially from the outer ring 118, having fastening openings124, by way of which the hub 112 is connected in a rotationally fixedmanner to the crown ring 108 (for example on the crown webs 110).

On the outer ring 118, a cover 126 is arranged on the upstream side ofthe hub 112 (that is to say on the rear side of the view in FIG. 3) asthe element maintaining the pressure difference. The cover 126 comprisesa circular-disc surface or a conical surface whose tip is situated inthe extension of the axis of the hub 112. An outer diameter of the cover126 corresponds substantially to an inner diameter of the crown ring108, and so the interior of the crown ring 108 is closed off against airrecirculation by the cover 126.

The cover 126 is fastened circumferentially at a multiplicity offastening openings 128 in the outer ring 118. Since the bearingstructure of the hub 112, in particular for transmitting the torque, isformed by the inner ring 114, the intermediate region 116 (for examplethe spokes 117 shown in FIG. 3) and the outer ring 118, the cover 126 isnot subjected to any transmission of force or transmission of torque tothe rotor blades 104 of the axial fan wheel 102. Accordingly, the cover126 may be thin-walled without any significant contribution to the massand to the moment of inertia of the hub 112 or of the axial fan wheel102. Preferably, the cover 126 is manufactured from aluminium sheet.

For example, the cover 126 may also close off an opening 130 between theouter ring 118 and the crown ring 108, which opening comes into beingdue to the hub webs 122 that ex-tend radially outward from the outerring 118.

The exemplary fan arrangement 100 shown in FIG. 3 comprises the axialfan wheel 102 and a radiator which is arranged upstream on thenegative-pressure side of the axial fan wheel 102. For the sake ofclarity, only a radiator trough 132 of the radiator is shown in FIG. 3.The radiator trough 132 comprises at least two cut-outs 134 for acooling-water circuit running in the axial direction, and slots 136 formounting the radiator trough 132, for example in a motor vehicle.

FIG. 4 shows a second exemplary embodiment of the axial fan wheel 102 inthe context of an exemplary fan arrangement 100. Features whichcorrespond to or are interchangeable with (in a structural or functionalsense) those of FIGS. 1 to 3 are provided with identical referencesigns.

In the second exemplary embodiment of the axial fan wheel 102 shown inFIG. 4, the spokes 117 between the inner ring 114 and the outer ring 118are designed as further rotor blades. These further rotor blades are anexample of the element maintaining the pressure difference.

For example, the spokes 117 comprise sections of a triangular surfacewhich is inclined at an angle of inclination to the plane of rotation.Alternatively, the spokes 117 comprise a curved surface, for example asection of a hyperbolic paraboloid, wherein the two edges of each spoke117 are not parallel to the plane of rotation of the axial fan wheel102. In the second exemplary embodiment shown in FIG. 4, the two edgesof each spoke 117 are skewed straight lines.

In the second exemplary embodiment of the axial fan wheel 102, the cover126 may be omitted. Preferably, the fastening openings 124 areintroduced directly in the outer ring 118 of the hub 112 (for examplewithout projecting hub webs 122), such that the outer ring 118 bearsagainst the crown ring 108 (for example without an opening 130 betweenthe outer ring 118 and the crown ring 108).

FIGS. 5A and 5B schematically show a front view and a rear view,respectively, of a third exemplary embodiment of the axial fan wheel 102in the context of an exemplary fan arrangement 100.

The third exemplary embodiment may be described as a variant of thefirst exemplary embodiment. Identical or functionally correspondingfeatures are provided with identical reference signs as in the firstexemplary embodiment of FIG. 3.

The cover 126 comprises a base surface that is planar and parallel tothe plane of rotation. On the upstream side (that is to say on thenegative-pressure side), further rotor blades 138 project from the basesurface in the axial direction. Each of the further rotor blades 138comprises an inlet side which is open in the direction of rotation andwhich is fluidically connected to the downstream side of the hub 112(that is to say to the positive-pressure side of the axial fan wheel102) by way of an opening, covered by the respective rotor blade 138, inthe base surface.

The development of the first exemplary embodiment according to the thirdexemplary embodiment not only allows the air recirculation through thethrough-passages 120 to be prevented, but an additional contribution tothe air transport through the hub 112 can supplement the main airtransport through the rotor blades 104. Also, in particular the secondand the third exemplary embodiment are combinable. For example, thecover 126 that is provided with further rotor blades 138 is able to bescrewed, on the upstream side, to the hub 112, the spokes 117 of whichare designed as further rotor blades.

FIG. 6 shows a refinement of the radiator trough 132 and of the casingring 106, which refinement is combinable with each exemplary embodimentdescribed above. At a radiator-side opening 140 of the radiator trough132, a collar 142 surrounding the opening 140 is formed. A circlediameter of the collar 142 is less, for example less by less than 5%,than a circle diameter of the radiator-side casing ring 106. The casingring 106 and the collar 142 are arranged in an overlapping manner in theaxial direction (that is to say in the horizontal direction in FIG. 6)such that, between the rotating casing ring 106 and the stationarycollar 142, a narrow air gap prevents the air recirculation at the edgeregion of the fan arrangement 100.

Even though the disclosure has been described with reference toparticular exemplary embodiments, it is evident to a person skilled inthe art that various modifications may be made, and equivalents may beused as a substitute. Furthermore, numerous modifications may be made inorder to adapt a particular situation or a particular material to theteaching of the disclosure. Consequently, the disclosure is not limitedto the exemplary embodiments disclosed, but rather encompasses allexemplary embodiments which fall within the scope of the appended patentclaims.

LIST OF REFERENCE SIGNS

-   100 Fan arrangement-   102 Axial fan wheel-   104 Rotor blades-   106 Casing ring-   108 Crown ring-   110 Crown web-   112 Hub-   114 Inner ring of the hub-   115 Diameter of the inner ring-   116 Intermediate region of the hub-   117 Hub spokes-   118 Outer periphery or outer ring of the hub-   120 Through-passage in hub-   122 Hub web-   124 Fastening opening in hub for crown ring-   126 Cover-   128 Fastening opening in outer ring for cover-   130 Openings between outer ring and crown ring-   132 Radiator trough-   134 Cut-outs for cooling-water circuit-   136 Slot-   138 Rotor blades in cover-   140 Radiator-side opening of the radiator trough-   142 Collar of the radiator trough

What is claimed is:
 1. An axial fan wheel comprising: a crown ringhaving a plurality of rotor blades; a hub having an inner ringconnectable to a drive shaft, having, for a purpose of torquetransmission, connection surfaces along an outer periphery of the hubwhich are connected to the inner ring and to the crown ring, wherein thehub has through-passages between the inner ring and the outer periphery;and at least one element, arranged in a rotationally fixed manner on theaxial fan wheel inside the crown ring, designed to maintain a pressuredifference in the axial direction when the axial fan wheel rotates,wherein the at least one element includes spokes for the transmission oftorque between the inner ring and the outer periphery, wherein the hubhas the through-passages between the spokes, wherein the at least oneelement further includes a cover that is configured to cover theinterior of the crown ring, wherein the cover is manufactured fromaluminium sheet, and wherein the inner ring is arranged outside a planeof rotation defined by the connection surfaces.
 2. The axial fan wheelaccording to claim 1, wherein a surface portion, projecting into a planeof rotation, of the hub between the inner ring and the outer peripheryis smaller than a surface portion, projected into the plane of rotation,of the through-passages between the inner ring and the outer periphery.3. The axial fan wheel according to claim 1, wherein a radial width ofthe through-passages is greater than a diameter of the inner ring. 4.The axial fan wheel according to claim 1, wherein the at least oneelement closes off the through-passages between the inner ring and theouter periphery, or the interior of the crown ring.
 5. The axial fanwheel according to claim 1, wherein further rotor blades are integrallyformed on the at least one element.
 6. The axial fan wheel according toclaim 1, wherein the spokes are designed as further rotor blades.
 7. Theaxial fan wheel according to claim 1, wherein the at least one elementis arranged rigidly on the hub.
 8. The axial fan wheel according toclaim 1, wherein the at least one element is manufactured from aluminiumsheet.
 9. The axial fan wheel according to claim 1, wherein the at leastone element does not transmit torque to the crown ring.
 10. The axialfan wheel according to claim 1, wherein a diameter of the at least oneelement is greater than an outer diameter of the outer periphery. 11.The axial fan wheel according to claim 1, wherein a diameter of the atleast one element is equal to or less than an inner diameter of thecrown ring.
 12. The axial fan wheel according to claim 1, wherein the atleast one element is arranged offset with respect to the hub in theaxial direction.
 13. The axial fan wheel according to claim 1, whereinthe axial fan wheel is used in conjunction with a radiator of a motorvehicle engine.
 14. A motor vehicle including a radiator and an axialfan wheel, comprising: a crown ring having a plurality of rotor blades;a hub having an inner ring connectable to a drive shaft, having, for apurpose of torque transmission, connection surfaces along an outerperiphery of the hub which are connected to the inner ring and to thecrown ring, wherein the hub has through-passages between the inner ringand the outer periphery; and at least one element, arranged in arotationally fixed manner on the axial fan wheel inside the crown ring,designed to maintain a pressure difference in the axial direction whenthe axial fan wheel rotates, wherein the at least one element includesspokes for the transmission of torque between the inner ring and theouter periphery, wherein the hub has the through-passages between thespokes, wherein the at least one element further includes a cover thatis configured to cover the interior of the crown ring, wherein the coveris manufactured from aluminium sheet, and wherein the inner ring isarranged outside a plane of rotation defined by the connection surfaces.15. The motor vehicle according to claim 14, wherein the motor vehicleis a utility vehicle.